In the A Song of Ice and Fire novels, the Graces are divided into several sub-orders, and each wears different colored robes to denote their function. The Graces are apparently an all-female clergy and many of them are of noble birth. However, it is unclear if this is an absolute requirement, or if it varies from one sub-order to the next:

The Blue Graces are skilled healers and surgeons, treating everything from plague to serious battle injuries (in this respect they are somewhat like the Order of Maesters in Westeros). One named Blue Grace is Ezzara, who appears in A Dance with Dragons.

The Red Graces are cult prostitutes. They are the only Graces that are allowed to have sex, while the others are sworn to chastity.

The White Graces are girls of noble birth who are too young to serve in pleasure houses. While not stated, they apparently join other suborders of Graces when they grow older.

The Green Grace is the high priestess, and there is apparently only one at a time in any given temple. The Green Grace of Meereen, Galazza Galare, becomes an advisor to Daenerys Targaryen during her rule in the city.

The Pink Graces serve as personal attendants to the Green Grace. It is unknown if they perform any other duties

Gold Graces and Purple Graces also exist, but their specific functions have not been mentioned.